The following article, often cited as a reference for Titanic's wireless telegraph configuration, was written over a year before Olympic's maiden voyage, and almost two years before Titanic's. The technology of wireless telegraphy advanced quickly during that period and by the time of Olympic's sailing, much of the information so well described in this article did not apply to the newest White Star Line flagship. Parks Stephenson has annotated the text with comments to describe the differences between the standard 1 1/2-kw standard marine set described by Mr. Bradfield and the 5-kw apparatus installed in both Olympic and Titanic.
Click on the underlined phrases in the text to read the annotations.
"THE ELECTRICIAN" MARINE ISSUE
June 10, 1910
BY W. W. BRADFIELD.
(Of Marconi's Wireless Telegraph Co., Ltd.)
Summary.After discussing the advantages and progress of wireless telegraphy for marine purposes, the author describes the Marconi plant used on board ship in detail. This may be classified as transmitting, receiving and emergency apparatus. In conclusion, particulars are given of the number of naval and mercantile marine stations in operation in the various countries.
Wireless telegraphy is now regarded as an essential part of the equipment of large ocean-going passenger vessels. It has reached this position partly through the sensational evidence afforded by the incidents of the ss. “Republic” and the ss. “Slavonia” as to how invaluable it may prove to ships in distress, but mainly through the experience gained regarding the general usefulness of an extended means of marine communication. Numerous cases have been published from time to time showing how passengers have made use of the facilities for sending messages to and from ships on the Atlantic and other routes. In the professional circles of the mercantile marine, however, more importance is attached to the fact that wireless telegraphy has destroyed the isolation of ships at sea. Apart from the anxieties thus relieved and the risks of loss and delay thus diminished, there are many economies, in connection with embarkation and disembarkation, which may be arranged when messages can be sent to ships at any point on their course. These points need not be laboured. The fact that in Lloyd's Register each ship carrying wireless apparatus is specifically marked, and that a special section of such ships has been added, shows that wireless telegraphy has attained an assured position among shipowners and underwriters.
Recent progress to this position has been very rapid. At the beginning of 1909 (after eight years of development) there were 125 ships of the mercantile marine fitted with Marconi apparatus. At the end of 1909 the number had risen to nearly 300, and at the present time the total is about 350, and is continuing to increase at a high rate. This increase has been accompanied by a marked development in the number of land stations erected, in course of erection and under consideration. And, apart from these conspicuous developments, the use of wireless telegraphy has become practically universal in our own and other navies, having been extended from battleships and cruisers to destroyers and submarines. There is every indication that what is now standard practice in the Navy will tend to become so in the mercantile marinethat is to say, the example set by the leading passenger steamship lines will be followed by all ocean-going and Channel passenger boats and also by cargo boats. The advance will probably be cumulative, as each installation on sea or land increases the value of the service to every ship making use of it.
It is interesting at this stage to survey the progress made on the principal trade routes.
North Atlantic.This is the route where wireless telegraphy has been most developed, owing in a large measure to the chain of shore stations established by the Marconi Company in Great Britain, Canada and the United States. All the leading vessels plying between European ports and North America are equipped, the total being 130, belonging to British, French, German, Dutch, Italian, United States and Greek companies. Under an agreement made last year, the shore stations of the Marconi Company in Great Britain passed into the hands of the Post Office, with the exception of the high-power stations at Poldhu and Clifden, the former being used for the transmission of news to Atlantic liners and the latter for the trans-Atlantic service.
South Atlantic.The great route between Europe and South America comes next in order of importance. Eighty-five ships are already equipped, owned by the Royal Mail Steam Packet Co., the Koninklijke Lloyd, and the principal Italian companies. With the completion of the long-range station at Coltano and the erection of shore stations in Brazil and the Argentine, further developments in this important trade route are certain to take place. Coast stations have been erected at Guaratiba, Ponta Negra, Ilha Raza and Rio de Janeiro in Brazil; at Punta del Este, in Uruguay; and at Bernal, in Argentina, on the River Plate.
South African.—Substantial progress has been made on this route. The Aberdeen Direct Line (Rennie Brothers) has used wireless telegraphy for some time, and the Union Castle has made a start with the ss. “Balmoral Castle.” A Marconi station is in course of erection at Durban, and when it is ready the White Star liners in the New Zealand service will be fitted. The White Star Australian boats are all being equipped. Further advances will follow the erection of shore stations by the Cape Government.
Eastern Route.—The potentialities of wireless telegraph developments on the great route through the Mediterranean to India, China and Australasia are enormous. Eleven P. & O. vessels and 16 Dutch vessels trading to Java are already fitted with Marconi apparatus. The ss. “Otranto,” of the Orient Steam Navigation Co., is the first ship of this line to carry an equipment, and it is intended to fit the entire fleet during the coming season. The Commonwealth Government has made a beginning with a scheme for a series of shore stations, and arrangements are being undertaken for a number of stations at points intermediate between Australia and this country.
The development of regular communication between an increasing number of moving stations has necessitated not only a carefully devised organisation, but a uniform method of working. This, in turn, has necessitated a practical standardisation of apparatus. At the same time, the demand for absolute reliability in the hands of ordinary operators has led to the evolution of a type of apparatus which is free from complications and is constructed to work continuously without derangement. From the accompanying illustrations it will be observed that most of the working parts are contained in solid boxes, which protect them from damage and limit the responsibilities of the operator to superficial adjustments and the ordinary business of receiving and transmitting messages. The advance in electrical design has been accompanied by a close attention to mechanical detail, with the result that failure on the part of the apparatus itself is practically unknown.
These points will emerge more clearly from the following detailed description of the standard 1 1/2 kw. Marconi set usually installed on ships. The everyday transmitting range of these sets varies from 70 to 300 nautical miles, according to the height, length and shape of the aerial, these factors being determined in turn by the dimensions of the ship; while the night range may be anything from two to three times the day range, according to the conditions of the atmosphere. They are designed to produce waves of 300 and 600 metres, with a simple change-over; and the receiving apparatus provides for tuned reception of all waves between 100 and 2,500 metres, the range of reception depending upon the aerial available and the power of the corresponding station.
Current (D.C.) is obtained from the ship's mains and led to a rotary converter, which supplies alternating current to the main terminals of a switchboard. (Emergency apparatus is always installed for working off a battery of accumulators in the event of the ship's supply failing—as was the case with the “Republic” after the collision.) The converter is designed to give an output of 1 1/2 kw., and to take current from the direct-current supply available. It has four poles, and runs at 1,500-1,800 revs. per min., with a frequency of 50 to 60 periods. Variation in speed is obtained by the field regulator.
Transmitting Apparatus.The low-frequency circuits consist of an adjustable inductance, the coils of a magnetic relay key, and the primary of a potential transformer connected in series and then to the two-line terminals of the switchboard. This circuit is opened and closed by the main switch, and operated by a Morse key actuating electrically the relay key. (Figs. 1, 2 and 3.)
The secondary of the potential transformer connects at the discharger through two air core protecting chokes with the primary high-frequency circuit. The transmitting condenser is connected to one side of the discharger and primary frequency tuning inductance to the other side. Between them is connected the primary of an oscillation transformer or transmitting jigger. The secondary of this transformer is connected at one end to the aerial and at the other to the top plate of a micrometer spark-gap, the bottom plate being “earthed” by connection with the iron shell of the ship. A tuning lamp and choke are put in shunt with a short length of the wire connecting the jigger secondary to the micrometer spark-gap. The transmitting set is completed by an aerial tuning condenser, which is used only when it is necessary to decrease the natural period of the aerial circuit in the transmission of the 300-metre wave.
Receiving Apparatus.The connection of the receiving apparatus with the aerial circuit is made at the top plate of the first micrometre spark-gap. From here a lead is taken to the aerial terminal of the tuner, the earth terminal of the tuner being connected to the bottom plate of the micrometer spark-gap.
The primary terminals of a magnetic detector are connected to the tuner, and the secondary terminals to a telephone and shunting telephone condenser.
Emergency Apparatus.In this a battery of accumulators, charged by the ship's dynamo, provides current to work an induction coil. A separate key is used for operating; or, in the cases where a special change-over switch is provided, one key is used for operating both circuits.
The aerial lead-in is connected, by means of a flexible wire, to a socket on an insulating pillar, which in turn is connected to one end of the induction coil secondary, the other end of which is connected to earth. When receiving, the aerial terminal of the tuner is connected by a flexible and plug to the socket on the insulating pillar.